Relative residuals in X-ray emissivity profile for the relaxed simulated cluster CL135 studied by Tchernin et al. (2020), for the region [0.5,  1] r₅₀₀ (ϵ ≈ 0.36), compared to the optimal ellipticity in the region [r₅₀₀, r₂₀₀] (ϵ ≈ 0.2). These optimal ellipticity values are obtained using the inner domain. For comparison, the relative residuals with respect to the spherical symmetry assumption are also shown. Here, x versus y means: |x−y|/x, with x and y being the triaxial profiles derived for a given ellipticity. The vertical lines indicate r₅₀₀ and r₂₀₀, respectively.